In many applications, a waveform needs to be sampled to determine its characteristics, including its frequency or phase. Several basic solutions are available to these questions. In one typical solution, analog components are used to obtain a comparison that includes both a magnitude and sign of a difference between an input and a reference signal. However, this typical solution suffers from the disadvantage that the analog components have a lack of precision in the comparison since the components have inherent timing limitations, including non-standard response and/or delay times.
In other typical solutions, digital logic components are used. However, when performing the frequency comparison, these typical digital solutions do not provide a linear output (i.e. an indication of how much higher or lower the input is to the reference.)